The US used RHA armor while the Germans used FHA armor. What are the differences and advantages or disadvantages of each type of armor. I have heard that RHA is stronger and better at stopping kinetic energy weapons. But I cannot seem to find any data on it.

The US used RHA armor while the Germans used FHA armor. What are the differences and advantages or disadvantages of each type of armor. I have heard that RHA is stronger and better at stopping kinetic energy weapons. But I cannot seem to find any data on it.

RHA is the same, uniform hardness and malleability throughout the entire plate, FHA is much harder on the front of the plate due to how it's treated, basically by shifting the carbon content (and in some cases, other alloys in the steel) to the front to get said hardness. making some projectiles more likely to deflect or shatter, however at the cost of making the center and back of the plate softer and the front more brittle and less malleable. (Brittle armor is more likely to crack and spall.)

The US used RHA armor while the Germans used FHA armor. What are the differences and advantages or disadvantages of each type of armor. I have heard that RHA is stronger and better at stopping kinetic energy weapons. But I cannot seem to find any data on it.

There are many different methods of face-hardening. In theory, face-hardening should allow you to maintain a ductile interior while having very high hardness on the surface. However, we know that German armour was brittle all the way through. Frankly, the problem with German armour is almost certainly that they had poor understanding of metallurgy.

From what I've read about the quality of German armour, it sounds almost like copying, ie- the people who ran the mills were just rote-copying procedure and didn't really understand the underlying principles of metallurgy, so when they ran out of a particular ingredient, they didn't know what to do.

From what I've read about the quality of German armour, it sounds almost like copying, ie- the people who ran the mills were just rote-copying procedure and didn't really understand the underlying principles of metallurgy, so when they ran out of a particular ingredient, they didn't know what to do.

Reminds me of a British intel report dated September 1945 analyzing German artillery(including tank) round design, how the designers at Krupp and Rheinmetall had taken notice to ballistic effects(round type and sloping with velocity determine the real penetrating power) but determined that they had it figured out in 1935, which dictated their designs for the war.

Whereas US experimentation with extremely long tank guns(i.e. T15 and T5 derivatives) showed them finding out new nuances to artillery ballistics well past the wars end.

Reminds me of a British intel report dated September 1945 analyzing German artillery(including tank) round design, how the designers at Krupp and Rheinmetall had taken notice to ballistic effects(round type and sloping with velocity determine the real penetrating power) but determined that they had it figured out in 1935, which dictated their designs for the war.

Whereas US experimentation with extremely long tank guns(i.e. T15 and T5 derivatives) showed them finding out new nuances to artillery ballistics well past the wars end.

I wonder if the Germans lost a lot of their technical expertise due to defection. After all, many people working on the US A-bomb program were Jewish scientists who fled Germany.

Huh, they list the M36 as "Slugger" in that last one. Never saw that before.

In my research and interviews around the use of the M36 to breach the Maginot fortress at Simserhof in December 1944, the crews always referred to this TD as "Slugger". And never as a "Jackson". The primary tactic was to get close and then bore-sight the 90mm into the fort's apertures and fire way with AP in an attempt to blind the German defenders. The Germans used the same tactic in 1940 in storming other Maginot forts using the 88 AA cannon. Plenty of guts in both accounts.

To those of you asking about the differences in steel quality, specially RHA and FHA...advantages disadvantages etc.

All of the major combatants of ww2 except for the Russians used medium hardness RHA for most tanks, or cast armor of similar hardness levels. The quality of the steel was really for all intensive purposes the same. A lot gets made of the tiny differences in manufacturing process etc, but the bottom line is that all RHA within certain hardness margins functioned about the same. Keep in mind I'm generalizing here, speaking broadly etc. Although a good example of how even poorly made RHA still more or less functioned as it should have is the Isigny tests on Panther G's which had known issues with their armor. The Panthers in those tests reacted pretty much exactly as you would have expected from steel without serious faults.

Medium Hardness RHA was chosen because it was found to have the best general purpose characteristics. Too soft and you lose effectiveness. Too hard and you lose effectiveness in certain situations. This is why most RHA varied between 240-300 Brinell for most thickness plates.

Regular solid shot AP shells could be make to have their noses shatter by face hardened plate, which was the main reason for using face hardened plate. For this reason, capped rounds became the norm generally speaking. The cap takes the impact force and prevents shatter. However it reduces straight line penetration in most cases vs RHA by a small amount, and APCBC specifically performs worse against sloped plate. APBC on the other hand generally performs much better at high angles of slope.

Extremely hard steel has a somewhat higher resistance against non-over-matching rounds, but once you get over 375 brinell over-matching rounds become a serious issue for high hardness steel. An example is the armor of the T-34. At 45mm it is over-matched by most rounds. The reduction in effective armor is quite alot, going from 122mm effective to 97mm at 450 Brinell hardness when faced with a 75mm shell.

Lastly you have cast steel. Cast armor got used alot because it was easier to shape etc. It does not resist as well as RHA. This is the reason that the M4A3, M4A3W, and Easy Eight all used 64mm of RHA sloped at 47 degress instead of the cast steel of the M4A1. It is almost never mentioned, but the later marks of Sherman had significantly better protection than the cast models. The 64mm of RHA at 47 degress offered 118mm of protection versus a 75mm gun like the KwK 48. The 51mm of cast steel on the M4A1 only offered about 93mm. To put that in context, the often derided armor protection of the Sherman in 1944 was sufficient to be immune to glacis strikes at ranges over 750m...the average engagement range in Europe. A massive improvement over the 1600m kill range of a M4A1.

I must say this video became a permanent bookmark on my browser, everytime I see someone spewing nonsense about american armour in WWII I link this video to them, it's even more serious when it's videos where a narrator is reading a text supposedly prepared by an historic consultant, as the company that makes war th*nder has done in one of their weekly videos

don't know whay but everyone still seems to forget that "the Sherman was sooooo Baaaaaad it won the war on both fronts"

I'm going to be efficient this week. Instead of spending a whole lot of time typing, I'm just going to link to a video. Preparing for the video took enough typing as it was, so it all evens out.

Background: A few months ago, the lads at the Flying Heritage Collection asked if I would be willing to give a talk at their annual Tankfest NorthWest event. Well, as it turned out, I certainly would.

Given a total lack of suggestion, I decided I'd continue on my Sherman/TD rant, with a larger audience. This audience expanded considerably by the presence of one of our lads with a video camera. He was unable to cover the Q&A section at the end, but if you have questions, I'll be happy to respond on the forum.